Find Opposite Edges Pairs For A 4-sided Polyfacet

[nier]

Hello

It looks like a simple problem, but I am having a hard time with it.

I have a 4-sided polygon face on a polgonal object with multiple faces.
I need to select both pairs of edges from thsi face which are opposite to each other.

I thought about getting the edges, then getting each edge vertices, and compare them so that if both vertices of an edge are not present on the other edge, they are opposite. But it all seems too complicated and ugly when I try to code it...

Any insights??

Thank you very much
Daniel

[joojaa]

Do a edge ring (ctrl + rmb) selection and then intersect that with edges of the polygon, probably easiet in the gui. If you want to script it then its also as easy to assume the other edge is edgeindex+2%4 Should yeld same rersont even if the quad is VERY maligned (you can get edges in index order with polyinfo).

[nier]

Thanks Jooja, seems much more simple...

I tried something out, and you can see why i think it looks very ugly... too many loops and checkings.
I have to do it all very fast, no time for good thinking, but it works......

I'll try your suggestion though, should make it much more simple....

Python code:

CODE
def oppositeEdges(f):
    #returns 2 pairs of opposite edges for a 4-sided face

    es = cmds.ls(cmds.polyListComponentConversion(f, ff=1, te=1), fl=1) #get edges

    pairs = []  #to store pairs of edges

    for e1 in es:
        vs1 = cmds.polyListComponentConversion(e1, fe=1, tv=1) #get vertices for edge 1

        for e2 in es:
            if e2 == e1:  #if looking at the same edge, skip
                continue

            vs2 = cmds.polyListComponentConversion(e2, fe=1, tv=1) #get vertices for edge 2

                        #check if the vertices from the first do not appear between the ones of the second
            if (vs2[0] in vs1) == 0 and (vs2[1] in vs1) == 0 and (e1 in pairs) == 0:  
                pairs.append(e1)
                pairs.append(e2)

    #reassemble the list so it has 2 elements containing the         
    return [[pairs[0], pairs[1]], [pairs[2], pairs[3]]]  pairs

[joojaa]

If your looking for speed dont use maya.cmds. Even a very convoluted loop done in teh api modlues is WAY faster because it has object level access.

Are you sure your not doing premature optimization?

Theres a trick to fast, its to use maya fundctions because they ARE api speed stuffs so even if you end up doing a lot more work and longer code ist usually faster. In factloger code ioftyen is faster than short and concice one. THeres another trick too grow 2 times